The present invention relates in general to semiconductor devices and, more particularly, to integrated circuits for interfacing with smart cards.
Smart cards are small plastic devices which contain one or more embedded integrated circuits for storing a user""s personal data and for executing software programs to run smart card applications. A smart card is programmed and the personal data is accessed with a smart card reader that has an aperture or slot into which the smart card is inserted. Terminals within the slot connect to terminals on the smart card to provide power and data connections for operating the smart card.
There currently are two standard types of smart cards: three volt smart cards that operate from a three volt power supply and five volt smart cards that operate from a five volt supply. Smart card readers detect which type of smart card has been inserted and provide the appropriate power supply voltage at the supply terminals. Portable smart card readers typically operate from a five volt battery, and include a direct current to direct current (DCxe2x80x94DC) converter which generates a three volt supply across the supply terminals when a three volt card is inserted and a five volt supply when a five volt card is inserted.
Because the aperture is accessible, smart card readers can be damaged if foreign objects or defective smart cards are inserted. For example, an inserted metal object can cause an overcurrent or other fault condition which damages the DCxe2x80x94DC converter or corrupts data stored on the smart card. However, existing smart card readers offer little or no protection against such fault conditions because they use integrated circuits housed in low lead count semiconductor packages and therefore do not have extra leads available for monitoring operating conditions. The low lead count packages are used because of their small size and low fabrication cost.
Hence, there is a need for an integrated circuit and method of monitoring a variety of operating conditions of a smart card reader which can be used with a low lead count semiconductor package in order to increase the robustness of the smart card reader while maintaining a small size and low manufacturing cost.